BrettM wrote:

But
through lane capacity is calculated from a 2s headway at whatever the
speed limit is.

Err, 2s headway is 30 vehicles per lane per minute _regardless_ of whatever
the speed limit is. Many years ago they increased the Freeway speed limit in
Perth from 80 to 100 so they "could get more cars on it". Even my mother,
who was 75 at the time, could see that that was bull****.

Theo